Discussion
Some older adult patients with RA develop complications as their joints are destroyed by the disease, resulting in functional disability or persistent weight-bearing pain. Conservative treatments, such as drug therapy or orthosis therapy, are unable to correct severe deformity of the ankle joints. In particular, weight-bearing joints in the lower extremities, such as the hip, knee, and ankle joints, tend to worsen or show a progression of osteoarthritic changes, and patients often complain of weight-bearing or gait pain.2 For damaged joints where pain or functional disability persist, joint surgery is sometimes indicated even when the DAS28 scores are maintained at low or moderate values. When joint destruction occurs in the lower extremities, surgeries such as knee or hip joint arthroplasties and ankle arthrodesis may be required.
Both patients in our study were over 80 years old, and tofacitinib (in Case 1) or methotrexate (in Case 2) maintained moderate disease activity. However, persistent ipsilateral ankle joint pain and walking disability indicated surgical treatment for the damaged ankle joints.
For destructive ankle joints due to RA, total ankle arthroplasty is one option. However, its long-term outcomes remain unknown and several complications, such as radiolucent line (73%), migration of the tibial component (21.1%), subsidence of the talar component (28.9%), and intraoperative malleolus fracture (7.7%), are concerning.18 Tibiotalocalcaneal joint fusion is another option. Furthermore, locking nail systems biomechanically show better stiffness than unlocking nail systems.13
For conservative treatment of moderately to highly destructive ankle deformities, orthosis (called the “MAX brace”19) or triamcinolone injections have been performed at our facility. In cases that are refractory to conservative therapy, we have performed surgical interventions such as talocrural joint arthrodesis with ankle arthroscopic synovectomy and tibiotalocalcaneal arthrodesis using a retrograde intramedullary ankle nail.
Mid- and long-term outcomes of retrograde intramedullary ankle nail fixation with fins for patients with RA have been reported.14−16 The mid-term result after intramedullary ankle nail fixation for 51 highly destructive ankle joint cases showed a mean follow-up duration of 71.6 ± 51.1 months and a mean postoperative JSSF score of 65.3 ± 14.9 (range, 30−84). However, nonunion of the subtalar joint was detected in 43.3% of cases (23 joints), and an absence of subtalar curettage and earlier postoperative weight-bearing were significantly associated with subtalar nonunion on multivariate analysis of risk factors for nonunion.14We performed subtalar joint curettage, and it took approximately 12 weeks for weight-bearing training in both cases. Neither of our cases showed subtalar nonunion.
Nagashima et al. reported 25 cases of severe hindfoot deformity due to RA that underwent intramedullary nail fixation with fins and were followed up for 7 years and 1 month.15 All cases achieved osseus fusion of the talocrural joint by 14 weeks postoperatively. Additionally, 23 cases achieved osseus fusion of the subtalar joints; the 2 exceptions were cases of mutilating type. The Japanese Orthopaedic Association (JOA) foot score also significantly improved from 35.9 ± 10.6 preoperatively to 64.3 ± 9.3 postoperatively, and the authors concluded that this procedure had satisfactory outcomes. For 30 RA cases that underwent ankle arthrodesis using this system, the long-term results were satisfactory because they showed that a high JOA foot score was maintained (64.3 points), even after an average postoperative period of 10.7 years.16
We used a finned intramedullary retrograde ankle joint nail (unlocking nail system) in these two cases for two reasons. First, this system is easier for surgical procedures than a locking nail system because inserting distal screws is not required. The nail has four fins with sharp distal tips; these fins effectively prevent the ankle from moving in various directions.11 In addition, we used a transfibular approach for these two cases, which provided good visualization and easy access to the autogenous bone graft using cancellous bone from the cut end of the fibula (or iliac bone). Second, it usually takes a longer time to correct highly destructive ankle deformities with a locking nail system, and longer time for the surgery would often cause postoperative surgical site infections.
Although this treatment is not appropriate in cases of severe osteoporosis, bony union was acquired in both cases, although Case 1 showed a radiolucent zone around the nail. The bone mineral density T-score of the left hip in Case 1 was -2.8. This patient was not diagnosed with severe osteoporosis; therefore, no treatment for osteoporosis was performed. In Case 2, the bone mineral density T-score of the left hip was -2.8. Because the patient had been treated with 4 mg/day of prednisolone, denosumab and vitamin D were administered to prevent insufficiency fractures.
Finned intramedullary retrograde ankle joint nails are inserted from the subtalar joint to the talocrural joint to prevent the nail from rotating. Weight-bearing adds a compressive force around the nail and promotes bony union.11 The intramedullary ankle nail system accepts weight-bearing in the early postoperative stage. In our patients, postoperative treatment included 3 weeks of using a patellar tendon-bearing brace to prevent weight-bearing on the affected joints.
The use of this type of nail limits the range of motion of the subtalar and ankle joints.11 However, since destruction of the subtalar joint was observed in both patients, we considered the use of this nail to be appropriate. Dorsiflexion and plantar flexion of the ankle joint relies not only on the talocrural joint but also on the Chopart joint.20 Both patients could therefore retain a partial range of motion of dorsiflexion and plantar flexion.
In conclusion, we presented two cases of RA affecting a unilateral ankle joint, with the symptoms of persistent weight-bearing and pain on walking. Intramedullary retrograde ankle nails with fins were inserted, and both functional outcome and disease activity scores improved 6 months after surgery.